15

Integrated

Circuit

Systems, Inc.

ICS952601

0701G—10/13/04

The CPU_STOP# signal is an active low input controlling the CPU outputs. This signal can be asserted asynchronously.

CPU_STOP# Functionality

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Asserting CPU_STOP# pin stops all CPU outputs that are set to be stoppable after their next transition. When the I2C

CPU_STOP tri-state bit corresponding to the CPU output of interest is programmed to a '0', CPU output will stop CPU_True

= HIGH and CPU_Complement = LOW. When the I2C CPU_Stop tri-state bit corresponding to the CPU output of interest is

programmed to a '1', CPU outputs will be tri-stated.

CPU_STOP#

CPU

CPU#

CPU_STOP# - Assertion (transition from '1' to '0')

With the de-assertion of CPU_Stop# all stopped CPU outputs will resume without a glitch. The maximum latency from the

de-assertion to active outputs is 2 - 6 CPU clock periods. If the control register tristate bit corresponding to the output of

interest is programmed to '1', then the stopped CPU outputs will be driven High within 10nS of CPU_Stop# de-assertion to

a voltage greater than 200mV.

CPU_Stop#

Tdrive_CPU_Stop, 10nS >200mV

CPU

CPU#

CPU Internal

CPU_STOP# - De-assertion (transition from '0' to '1')